Emerging Exoplanet Resources

by Paul Gilster on January 20, 2010

The Exoplanetology site is developing a tool for those in need of quick exoplanet information. The Exoplanet Seeker is an interface that will make it easy to query various exoplanet databases, including the Extrasolar Planet Encyclopedia, NASA’s PlanetQuest New Worlds Atlas, the Exoplanet.org site and other sources like the Wikipedia and SIMBAD. Each of these sites has its own strengths, from light curves to graphical charts, so bringing them together will be helpful once early bugs in the interface (producing frequent failed queries) are resolved.

From tools on the Net to tools in space, it’s always interesting to speculate on what’s in the pipeline. Maybe ‘pipeline’ is too strong a word, though, because tools like the Transiting Exoplanet Survey Satellite (TESS) have to be approved by NASA, which is willing to consider an earlier version of the instrument it rejected but can offer no promise of success. Nonetheless, the results from CoRoT and the early detections of Kepler (not to mention the possibilities of WISE in finding nearby brown dwarfs) keep space instrumentation in sharp focus.

We’ve looked at TESS before, noting that its six wide-angle lenses would be put to use flagging stars with planets, building a list that the James Webb Space Telescope (to be launched in 2014) would then study in greater detail. What’s interesting about TESS, as this short article in Popular Science points out, is that it would scan a chunk of sky some 400 times larger than Kepler. That involves 2.5 million of the closest stars, a search that should return an abundance of interesting worlds to study.

Image credit: MIT.

The thinking of the TESS team, according to this MIT news release, is that between 1600 and 2700 planets might be found in the first two years of observations, including between 100 and 300 small, rocky worlds. The light curves produced by the planetary transits TESS observes would then be passed along to observatories on the ground and slated for spectroscopic analysis by the Webb instrument. The latter could potentially reveal details about planetary atmospheres and their constituents. Expect a new TESS proposal to be submitted this year to follow up an earlier initial feasibility study.

Meanwhile, we continue to watch the development of the Webb telescope with great interest. Mark Clampin (NASA GSFC), discusses the possibilities for planetary spectroscopy in an instrument originally designed to search for the earliest galaxies. JWST will be able to extract a lot of information from a planetary transit:

“By comparing the two spectra for the star (in and out of transit), we can extract the planet’s spectrum and learn about the planet’s atmosphere. We have to collect a lot of infrared light — a billion or more photons — for each spectral element to isolate features. Webb is perfect for this kind of study.”

TESS could be quite useful in feeding targets to JWST, but the latter will also be doing planet-hunting of its own using coronagraphic techniques that block the light of stars so planets around them are more readily visible. Clampin continues:

“Webb will show us what the ‘exoplanet zoo’ looks like. This telescope will be very good at observing and taking spectra of gas giant planets, and we can take some spectral data on smaller planets, too, about Neptune-sized. Our telescope will also zoom in to study newly discovered super Earths — planets bigger than Earth but smaller than Neptune.”

Exciting times ahead as we contemplate our next steps in space-based observation, especially the deployment of JWST’s 25 m2 collecting area. Will JWST be able to tell us whether life exists on distant terrestrial worlds? Probably not, though Clampin isn’t above hedging his bets:

“A true Earth twin would be too small to emit enough infrared light from its atmosphere for Webb to pick up. Still, every time scientists make statements like that, someone proves them wrong. Transit science is changing so fast, it’s hard to say exactly what wonders Webb’s hunt will turn up.”

It’s good to hear that the TESS project is still alive. An all-sky exoplanet survey will add immensely to our knowledge of exoplanet populations and features.
Having a little bit of overlap with Kepler provides some welcome redundancy
in the event of equipment faults.
Latest mission manager update from the Kepler website mentions some problems with the MOD-3 CCD pair. It’s unknown at this time if there is a work around for it.
I wonder if this might become a continuing problem as the spacecraft ages and is further exposed to cosmic rays and radiations. We might see a ongoing deterioration of the CCD array or other systems.
I fervently hope Kepler will achieve it’s goals before there is a fatal failure,space is a harsh environment.
Though TESS may not be able to detect Earth analogs around Sun-like stars I think it will certainly provide a wealth of new discoveries. Particularly of interest is the stated goal of examining all M-Dwarfs within a 50 parsec radius of home.

Sounds like a great development. Of special interest to me is the idea of blocking light from stars to study exoplanets further – could this be applied more widely? I always thought that the fact that we rely on planets to transit between their star and us is a big limitation on exoplanet discovery. What about all the exoplanets that don’t transit? I’m sure that finding those would increase numbers considerably. Edit: I checked wiki and astrometry would help in this case, if we could get it down precisely.

One thing I’ve noticed about studying the world and universe is that things are often stranger than conservative assumptions. In fact, the more we study, the more strange things we find! Our understanding has gone from immutable heavens with earth in the center, to an expanding, bending universe with black holes, supernovas and numerous galaxies.
As far as observing exoplanets, I believe there is a wide variety of them. The fact that we’ve found so many “hot jupiters” and super-earths is because those are the easiest to find with our methods. As we improve our search, smaller and colder gas giants will be found, as well as smaller terrestrial planets that are Earth-sized or smaller that orbit further away (perhaps in the goldilocks zone?)

bigdan201, The SIM lite mission will use astrometry to detetect non-transiting earth-sized planets around stars but we wont be able to get any info on the atmospheres using astrometry. We need space based occulters, coronographs or interferometers to do this. Several of these mission designs have been proposed. Looks like nasa may go with the occulter (starshade) concept used in conjunction with the James webb space telescope.

Each method has its limitations. The transit method is good as in the case of kepler becuase the sample size is so big we can extrapolate the results through the whole galaxy basically telling us how many “earths” we should expect to find around stars near our own solar system. Those other methods are limited in range and have a much smaller sample size than kepler limited to stars within 100 ly.

Expect things to pickup once the kepler results are in (3 years) assuming theyre positive!

Readng further, I see that there’s a number of methods for finding exoplanets, but as you said, each has its own limitation. Expanding the repertoire of observation tools will certainly show us more exoplanets.
For example, I found this chart:

From left to right is distance from the star, and up and down is mass. Our own solar system planets are in grey as a reference.

As you can see, the vast majority of exoplanets we’ve found are gas giants which are close to mid-range distance from their star. There’s a few gas giants which are further off, and a few super-earths which are close to midrange.
I believe that with good research, the large blank areas on the chart will all be filled in with dots… maybe an emphasis on some areas more than others, but I think the variety of exoplanets will be scattered across the graph.

One of the interesting features of the exoplanet mass-period diagrams is the apparent existence of two main clumps of gas giants: the hot Jupiters at roughly 3 days, and the eccentric Jupiters at periods upwards of 100-200 days or so. There seems to be a real deficiency of giant planets at intermediate periods: there’s no particular reason why radial velocity surveys should fail to find massive planets in this region if they exist.

Incidentally the median orbital period for the radial velocity planets listed on EPE is about 200 days or so: despite the significant observational biases of radial velocity and transit surveys towards finding close-in giant planets, roughly half of the known extrasolar planets fall into the category of eccentric Jupiters.

Here we go again on TESS, which could be very useful. If the MIT community was serious about getting TESS funded they would propose a joint program with Dr Webster Cash and his New World’s Imager which would in turn further leverage the JWST. What is needed is a combined cost effective program that includes JWST, TESS and New World’s Imager into a single architecture that can be used to explore the immediate area around Sol/Terra in detail out to about 60 light years and with a special focus on the first 12 Light Years.. In essence, what is needed is a combined cost-effective architecture that can be fully executed with the requisite data being received by 2020. In addition, some of the very valuable Habitable Moons and Ground Based Transit Detection work needs to be included as well. Bottom line, it takes both an architecture and a solid goal along with a cost-effective program plan to gain Government support in the time of major budget deficits. But it can be done with the right story.

So far, the U.S. Government is seeing a collection of Scientific “Hobby Horses” instead of a focused and cost effective Architecture and program plan that would yield full situational awareness out to about 60 Light Years by 2020. This could be done for a couple of Billion (less the cost of the JWST) if an interdisciplinary approch was adopted.

The same general issue applies to the work on the new Icarus Project for Interstellar Travel. Lets take an Architecture based incremental approach that spans the entire decade 2010-2020 to adopt the right concept and then refine it as new technology is invented over the next 10 years.

Also, at least initially lets separate a trip to Alpha Centuauri from all of the other potential Interstellar Trips since if there is actually something there and the above “Situational Awareness Program” detects something of interest then we might actually be able to engineer a viable and cost effective ship that does “Interstellar Travel” within 5 Light Years of Sol/Terra within the next 65 years. As one looks at options for Icarus-2 perhaps a potential trip to Alpha Centuari should be viewed differently and as more of a long Interplanetary Trip within the “Interplanetary Zone of SOL/Terra spanning a 5 Light Years radius as oppossed to a real Interstellar Trip that could span 10’s of light years and may be much harder to accomplish over the next few hundred years. In short, there is Alpha Centuari and there is everything else.

Charter

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last nine years, this site has coordinated its efforts with the Tau Zero Foundation, and now serves as the Foundation's news forum. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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